Quick Autobox Question

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Rachelkgr said:
Hmmm never heard about this lock up thing, does it sound like a 5th change?
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Yep...what it does is it stops the torque convertor from slipping i.e. when you go to accelerate the revs rise then the speed increases...with the TC Locked up, the slippage stops so in effect when you accel. there should be no rise in revs without a rise in speed...it can feel like another gear being selected as the revs tend to drop a few hundred...but it is there to effectively lock the gearbox to the engine to maximise economy!
 
I wish there was an override button for the torque converter to make it stay in lockup. It becomes a game to get them into lockup! Its especially annoying in a gems as they are gutless low down they need to be doing 45+mph to go in. Where as a gently driven thor will go in at 34/35mph. I hadn't realised they will also do it in 3rd will have to do some experimenting. Accelerating in lockup is far more satisfying to me as you can use the torque properly without its revving for no reason. The 300zx's I used to have suffered from the same "old auto gearbox" syndrome!
 
quavey said:
I wish there was an override button for the torque converter to make it stay in lockup. It becomes a game to get them into lockup! Its especially annoying in a gems as they are gutless low down they need to be doing 45+mph to go in. Where as a gently driven thor will go in at 34/35mph. I hadn't realised they will also do it in 3rd will have to do some experimenting. Accelerating in lockup is far more satisfying to me as you can use the torque properly without its revving for no reason. The 300zx's I used to have suffered from the same "old auto gearbox" syndrome!
Click to expand...

Torque convertor lock up occurs at around 50mph in top gear on all models. Lock up in third occurs at around 40mph. I often hold the box in third to take advantage of the lower lock up speed:)
 
So if you are motoring in D, you can change to 3rd if constant speed is around 40mph? Can you then go back into D to accelerate and use 4th (and lock up in 4th). I must admit that I have not ever changed whilst motoring, is this okay to do? (sorry - this is the first auto I've had ...)
 
plumbfisher said:
So if you are motoring in D, you can change to 3rd if constant speed is around 40mph? Can you then go back into D to accelerate and use 4th (and lock up in 4th). I must admit that I have not ever changed whilst motoring, is this okay to do? (sorry - this is the first auto I've had ...)
Click to expand...
You can manually select 1,2 or 3 and the box will make the appropriate downshifts at the most appropriate road speed... i.e. if you select 1 on the motorway, the box will NOT change down to first until such time as the vehicle speed is reduced to a point where 1st gear is safe to select...

if you are in D, you can select 3 and the box will downshift (if it is safe to do so) and then hold 3 until you select D again....basically this manual selection limits upshifts...so if you select 3, it limits shifts to 1,2 & 3 only....
 
Thanks for that ... hours of new fun to be had trying to get it to lock up in 3rd. It does feel much better when the torque converter is locked up - agree with previous comment, it would be good if there was such a thing as a button to do it ...
 
plumbfisher said:
Thanks for that ... hours of new fun to be had trying to get it to lock up in 3rd. It does feel much better when the torque converter is locked up - agree with previous comment, it would be good if there was such a thing as a button to do it ...
Click to expand...
I use third or second for engine braking on slow descents and third on speed restricted climbs or just pootling at 40, both actions will save fuel as the engine does not drop to idle on the overun so the fuel shut off operates and on the climb or pootling, the torque convertor is locked. You can accelerate in third then shift to D when you reach 60/70 if you wish.
 
Datatek said:
I use third or second for engine braking on slow descents and third on speed restricted climbs or just pootling at 40, both actions will save fuel as the engine does not drop to idle on the overun so the fuel shut off operates and on the climb or pootling, the torque convertor is locked. You can accelerate in third then shift to D when you reach 60/70 if you wish.
Click to expand...

Sounds if you should have bought a manual:p:D:D:D
 
In quite a few cars the gearbox software is upgradeable so you can change the profile at which shifts occur and the torque converter locks up. Did that on my miggy. Not sure if you can do it on the P38 though.
 
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